Pull in latest backstage chart using a new Kptfile

• Add a Kptfile at ./chart/Kptfile pointing to the appropriate chart from https://github.com/backstage/charts
• Pull in the latest chart using kpt pkg update ./chart@appropriate-git-tag-here
  • Ensure the chart we pick is compatible with the app version available to us in the new IronBank backstage image (https://registry1.dso.mil/harbor/projects/3/repositories/opensource%2Fbackstage%2Fbackstage)